Enhanced photocatalytic hydrogen production over conjugated polymer/black TiO2 hybrid: The impact of constructing active defect states

Utilization of noble metal (e.g. Pt, Au) as co-catalyst seems always indispensable for a photocatalytic H-2 production catalyst because most semiconductors lack sufficient active sites. Herein, some non-noble metal active states, Ti3+/Ov (oxygen vacancies) and surface amorphization structure, are introduced into anatase TiO2 nanoparticles by ball milling them with TiH2 to prepare black TiO2. And then, an organic/inorganic hybrid (BE-black TiO2) containing a conjugated polymer (BE, a modified poly-benzothiadiazole flake) and black TiO2 is fabricated and investigated for photocatalytic H-2 production without noble metal co-catalyst. Compare to BETiO2 catalyst, the BE-black TiO2 exhibit a similar to 30% enhancement for H-2 production activity under visible light (lambda > 420 nm) irradiation. Combining the structural characterizations, comparison of H-2 production rate and electron transfer behavior analysis, it is found that these active states play key role in the enhancement of photoactivity through narrowing the band-gap of TiO2, accelerating photoelectrons transfer from BE to TiO2, acting as electron traps and reaction sites for H-2 production.